Service manual
90-898303
4-26
DDT TEST
IMPORTANT: A fouled or faulty MAP sensor displays a default value of
approximately 14.7 psi.
1. With the DDT connected, start the engine.
2. Quickly open the throttle and close it again while observing the MAP sensor
readings on the Data Monitor function of the DDT.
3. If the sensor responds quickly to the changes in throttle position, the sensor
is good.
4. If the MAP sensor does not change, or changes slowly, disconnect and
visually inspect the sensor opening for blockage by oil. Clear the opening and
re-install the sensor. Repeat step 3.
Another sign that the MAP sensor is the problem is if the MAP sensor range of
values changes by more than 2.1 kPa (0.3 psi) while the engine remains at a
constant rpm and throttle opening.
Example: With the engine operating at a constant 2000 rpm, the MAP
numbers change from 93.8 kPa (13.6 psi) down to 92.4 kPa (13.4 psi) and
then up to 95.1 kPa (13.8 psi), and back again. This indicates a problem with
the MAP sensor. If the readings are incorrect, replace the MAP sensor.
VOLTAGE TEST
IMPORTANT: The Propulsion Control Module (PCM) is dependable and
should not be replaced before testing the sensor or wiring harness. The
corrosive environment combined with vibration suggests that most
problems occur with either the wiring or the sensor.
NOTE: Shake or move the harness and connector by hand as you perform the
following tests. If the voltmeter readings vary during the tests, a broken, loose,
or corroded wire is most likely causing the failure. Repair the problem wire and
retest the circuit as follows.
1. Set the key switch to RUN with the engine off.
2. Disconnect the sensor from the harness connection.
3. Visually inspect the pins at the sensor and the wires coming from the
connector. Look for broken, bent, or corroded pins at the sensor and loose,
broken, or corroded wires at the connector. Replace components as
necessary.
4. Connect a voltmeter across the PPL/YEL and the BLK/ORN wires at the
connector.
Example:
Lead to PPL/YEL
Lead to BLK/ORN
5+ Volts
Notes
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